Doctors said Finley Boyle suffered massive brain damage as a result of the Dec. 3 incident at Island Dentistry for Children, in Kailua.
The facility has since closed, CNN reported Saturday. The dentist, Lilly Geyer, could not be reached for comment.
Finley's family is suing Geyer and her former practice after the girl was given five forms of sedatives prior to the root canal, KGO-TV, San Francisco, reported.
The suit alleges there were no medical devices or procedures in place at the office to address medical emergencies such as the one Finley suffered. Additionally, the suit contends the girl was left unattended and sedated for 26 minutes.
Doctors said once Finley's heart stopped she suffered severe brain damage due to the lack of oxygen, leaving her in a "persistent vegetative state" for days. She was transferred from a hospital to hospice where she died Friday night.